Manganite

• Braunmanganerz
• Braunstein
• Glanzmanganerz

Manganite, as Braunmanganerz, Glanzmanganerz or short brown stone known ( not to be confused with the mineral group of brown stones), is a commonly occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the monoclinic crystal system with the chemical composition of γ -MnO (OH ), that consists of equal parts of manganese in the face-centered cubic modification, oxygen and hydroxide ions (OH ).

Manganite most developed prismatic and along the c- axis crystals and striped knee-or cross-shaped crystal twins, but also acicular and granular to massive mineral aggregates or concretions. Also pseudomorphs after calcite are known.

Manganite is usually opaque and grayish black to black in color with reddish-brown to black stroke color. In the thinnest layers and splinters it can, however, be reddish translucent. On the visible crystal faces shows strong and occasionally colorful iridescent metallic luster, fracture surfaces and massive aggregates, however, are dull.

Special Features

The crystal water contained in the manganite escapes only at about 200 ° C. In concentrated hydrochloric acid, the mineral dissolves, chlorine deposits. Before the blowpipe is reflected in the borax bead, the manganese reaction.

With time goes by weathering in manganite, pyrolusite, with the already existing striation often is always full of holes.

Etymology and history

Was first discovered in manganite Ilfeld in the district of Nordhausen ( Thuringia) in the southern Harz and described in 1827 by Wilhelm Ritter von Haidinger, who named the mineral based on its manganese content.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the manganite belonged to the mineral class of " oxides and hydroxides " and then to the Department of " hydroxides and oxide hydrates ( hydrous oxides with layered structure ) ," where he along with akaganeite, boehmite, diaspore, Feitknechtit, Feroxyhyt, goethite, Groutit, lepidocrocite, schwertmannite and Tsumgallit the " akaganeite group " with the system no. IV/F.06 formed.

The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the manganite also in the class of " oxides and hydroxides ," there, however in the new department of " Hydoxide (without V or U ) " a. This division, however, is further divided by the possible presence of OH - groups and water of crystallization, and the crystal structure, so that the mineral according to its composition and structure in the sub-department " hydroxides with OH, excluding H2O; Chains of edge -sharing octahedra " is to find where it forms the unnamed group 4.FD.15 the only member.

The classification of minerals according to Dana assigns the manganite into the class of " oxides and hydroxides " and there in the department of " hydroxides and hydroxy- oxides " one. Here he is the only member of the unnamed group 06:01:03 within the sub-division of: to find " hydroxides and hydroxy- oxides having the formula X3 O OH ".

Modifications and varieties

The connection γ -MnO (OH) trimorph and occurs in nature in addition to the monoclinic manganite more than trigonal Feitknechtit crystallizing and crystallizing as orthorhombic Groutit ago.

Education and Locations

Manganite forms ( 200-100 ° C), but also in secondary manganese ore passes through hydrothermal deposition at relatively low temperature. He seldom is also produced by sedimentary deposition or metamorphic transformation in manganese-rich rocks. Accompanying minerals are among other Braunite, barite, calcite, goethite, hausmannite, pyrolusite and siderite.

Worldwide, manganite so far (as of 2011) are detected at around 650 localities. It is known especially its type locality and other localities Ilfeld in the Harz by Druze finds with up to 4 cm large crystals. In addition, could the mineral in Thuringia still at Kamsdorf and long meadows, and at several locations in the Black Forest in Baden- Württemberg; Lichtenberg and hard Koppe ( Sailauf ) in Bavaria, in the district of Gießen, in Steeden, Upper -Rosbach and Wetzlar in Hesse; Peine in Lower Saxony; Sauerland and winners district of North Rhine -Westphalia; in several regions of Rhineland -Palatinate; at Wadern in Saarland; Mansfeld be found in Saxony- Anhalt, and at Schneeberg in Saxony.

In Austria manganite occurred mainly in several regions of Carinthia, Styria and Upper Austria as well as in Baunzen in the Lower Austrian town of Purkersdorf. In Switzerland, the mineral in the communities Tinizong - Rona and Ausserferrera in the canton of Graubünden in Thayngen in Schaffhausen and in Turtmann was found in the Valais.

Other localities are Argentina, Australia, Belgium, Brazil, Bulgaria, Chile, China, Finland, France, Gabon, Georgia, Ghana, Greece, India, Iran, Ireland, Italy, Japan, Canada, Cuba, Madagascar, Morocco, Mexico, Namibia, New Caledonia, New Zealand, Norway, Pakistan, Poland, Portugal, Rwanda, Romania, Russia, Sweden, Slovakia, Spain, South Africa, South Korea, Czech Republic, Turkey, Ukraine, Uzbekistan, the United Kingdom ( UK) and the United States of America (USA).

Crystal structure

Manganite crystallizes in the monoclinic space group P21 / c ( Raumgruppen-Nr. 14) with the lattice parameters a = 5.304 Å; b = 5.277 Å; c = 5.304 Å and 114.38 ° β = 4 and formula units per unit cell.

Use

Manganite is an important manganese with a manganese content of up to 62.5 %.